Power plant installation



Sept. 11, 1962 H. J. BLASKOWSKI 3,053,049

POWER PLANT INSTALLATION Filed April 28, 1958 Economizer EconomizerSteam Turbine Gas Turbine Generator Generator INVENTOR Henry J.Bloskowski $145M fat ATTORNEY bustion of the fuel within the boiler.

United States Patent ()fiice 3,53,049 Patented Sept. 11, 1962 3,053,t)49POWER PLANT {INSTALLATION Henry J. Blaskowslri, New York, N.Y., assignorto Conlbustion Engineering, like. New York, N.Y., a corporation ofDelaware Filed Apr. 28, 1958, Ser. No. 731,521 3 Claims. (Cl. 60-49)This invention relates generally to a power plant installation ororganization employing a gas turbine and boiler combination.

More particularly the invention involves this combination wherein thequantity of exhaust gases from the gas turbine is such that it providesan oxygen supply much greater than that required by the boiler tosupport com- In accordance with the invention a portion of the exhaustgases from the turbine are introduced into the boiler together with thefuel with which the boiler is fired with these exhaust gases supplyingthe oxygen necessary to support combustion of this fuel. The portion ofthe gases that are not introduced into the boiler are directed through abypass duct within which is positioned economizer surface f the boilerand also within which is positioned a low temperature superheatersection which is in series flow relation with a high temperaturesuperheater section located within the boiler. Means are provided tocontrollably proportion the gas turbine gases introduced into the boilerand passed through the bypass. The organization is such as to provide avery eificient operation with the gas turbine gases having theirtemperature lowered to the point so that they can economically bedischarged to atmosphere and at the same time a control of the superheatsteam temperature is obtained.

Moreover, with the invention the boiler may be designed so that it canbe operated without the turbine as when the turbine is shut down.

Accordingly, it is an object of this invention to provide an improvedpower plant installation employing a combined gas turbine and steamgenerator or boiler.

Other and further objects of the invention will become apparent to thoseskilled in the art as the description proceeds.

With the aforementioned objects in view, the invention comprises anarrangement, construction and combination of the elements of theinventive organization in such a manner as to attain the results desiredas hereinafter more particularly set forth in the following detaileddescript-ion of an illustrative embodiment, said embodiment being shownby the accompanying drawing wherein the single figure is a diagrammaticrepresentation of a power plant installation embodying this invention.

Referring now to the drawing the illustrative embodiment of theinvention depicted therein comprises a gas turbine 16 that is of thetype which produces substantially the same quantity of exhaust gasthroughout the range of its operation, as for example, a single cycle,single shaft gas turbine. This turbine receives the hot gas supply fromburners 12, which, in turn, receives compressed air from a compresserthat is not here illustrated. The exhaust from turbine exits into duct14, which, at the location 16, is divided into supply duct 18 that leadsto boiler 20 and into bypass duct 22 which leads to stack 24 Via passage36. Boiler 20 is tangentially fired in a conventional and well knownmanner by burners 26 and the exhaust turbine gases from supply duct 18are admitted into the boiler through these burners. With these gases,which contain about 80% of the oxygen found in free air, supplying theoxygen requirements to support combustion of the fuel introduced intothe boiler.

This illustrative boiler has the walls of its furnace into which thefuel is tangentially introduced and burned lined with steam generatingtubes and it is provided with a steam and water drum 28 and mud drum 30between which there is disposed steam generating tubes in theconventional manner. Forming part of this boiler installation is thehigh temperature steam heating surface 32 which is in the form of aseries of tube platens or groups in spaced relation across the boilerwith there being suitable baffles provided so that the combustion gasesflow in the boiler as is indicated by arrows 34. The combustion gasespass through the passage 35 into duct 36 within which is positionedeconomizer surface 38 of the boiler with these gases after traversingthis economizer surface passing into stack 24.

In order that the temperature of the turbine exhaust gases will bereduced to a suitably low value that these gases may economically bedischarged to stack 24 there is provided in bypass duct 22 theeconomizer surface 4-2 which is supplementary to the economizer 38 andheats the water that is introduced into the steam and water drum 28 ofthe boiler with this surface 42 being a part of the surface for boiler20. Also positioned in bypass duct 22 and upstream of economizer surface42 is the low temperature superheater section 44. This superheater 44receives steam from steam and water drum 28 through conduit 46,initially superheats this steam to some extent with the then superheatedsteam being conveyed to the high temperature superheater 32 by conduit48. In high temperature superheater 32 the steam is finally superheatedto its desired temperature and is discharged through conduit 50 whichleads to steam turbine 52. Low temperature superheater 44 is so relatedto the high temperature superheater 32 that the amount of heat impartedto the steam in high temperature superheater 32 is much greater thanthat imparted to the steam in passing through the low temperaturesuperheater 44. Of course, the temperature head, i.e., the temperaturedifierential between the steam and the gases passing over thesuperheater, in low temperature superheater 44 is much less than in hightem perature superheater 32. The reason for having a large difference inthe heat absorbing effectiveness of these two superheater sections willbe apparent hereinafter.

Gas turbine It} drives generator 52 while steam turbine 54 drivesgenerator 56. Each of these generators is connected through suitableconductors to a common buss 58, which, in turn, connects to a varyingload.

Engineering studies and operating experience have shown that maintaininga constant weight flow of gas over a superheater in a boiler through awide range of loads causes a rise in total steam temperature with adecrease in load. This characteristic is of course contrary to thatexhibited by conventionally fired boilers and poses a serious problem ofsuperheat metal selection, protection and control. Another problem thatis encountered in a combination such as being considered herein is theoperation of the steam generator independently of the gas turbine aswhen the gas turbine is shut down for some reason or other. It may bedesirable to obtain the same capacity and steam temperature when theboiler is fired conventionally using atmospheric air. Under thisoperation the temperature of gases generated in the boiler for aparticular load on the boiler is much greater than that produced withcombined boiler and gas turbine operation. This is so because theeconomizer surface in the bypass that is employed to reduce thetemperature of the turbine exhaust gases is not eifective so that for asimilar load on the boiler much more fuel must be fired into the boilerto make up for the loss of this surface and generate the required amountof steam. This increased gas weight and temperature of course effectsthe superheat tending to increase it.

Both of the aforementioned problems are solved by dividing thesuperheater into a low temperature section 44 and a high temperaturesection 32 as described hereinbefore. Only sufiicient superhea-t surfaceis provided in the high temperature section 32 to give the requiredsteam temperature at the desired load when the boiler is operatedindependently of the gas turbine, i.e., only sufficient superheatersurface is installed to obtain full steam temperature with coldairfiring. Fan 33 supplies the air in this instance. The additional surfaceprovided in low temperature section 44 is that amount of surface that isrequired for combined operation of the boiler and the gas turbine whereonly turbine gas is supplied to the boiler furnace to supportcombustion. With this organization boiler 20 may be operated When thegas turbine is shut down and the desired steam temperature obtained andwhen combined operation of the gas turbine and boiler is bad theadditional heat required for superheating the steam is picked up in thelow temperature superheater 44 and accordingly with this combinedoperation the required steam temperature is also obtained. A furtheradvantage of this arrangement employing superheater section 44 in bypass22 and upstream of economizer 42 is that there is a reduction in theamount of heat that must be imparted to economizer surface 42 in orderto sufiiciently reduce the gas turbine gas temperature so that aftertraversing the surface 33 it may be discharged to stack 24- therebyreducing the possibility of and the amount of, if any, steaming in thiseconomizer surface with it being desirable to maintain steaming in theeconomizer at a minimum so that scale and deposits will not form in theecono-mizer tubes.

A control is provided for the proportioning of the gas turbine exhaustgases through the supply duct 18 and the bypass duct 22, i.e., theproportioning of the gases that goes to each of these locations isadjustably controlled. This control is in the form of adjustable damper60 located at the inlet of supply duct 13 and adjustable damper 62located at the inlet of bypass duct 22 with damper 62 being one of aplurality of dampers disclosed in side by side relation across the ductentrance. It will be appreciated that the represented dampers are onlyillustrative of a control to controllably proportion the turbine exhaustgas flow through each of these ducts. It will further be appreciatedthat if no other change in the system is made, i.e., if the gas turbineand the boiler loads are not changed, an increase in the proportion ofthe gas turbine exhaust gases passing through bypass duct 22 relative tothat through duct 18 will decrease the temperature of the steamdelivered to the steam turbine while an increase in the proportion ofthese gases delivered to the furnace by duct 18 will increase the steamtemperature.

In the operation of this power plant system wherein the gas turbine andthe boiler are eifectively connected to and supply a common load, whichis a variable one, there are three possibilities with respect tooperation of the system as the load changes. The gas turbine and boilermay both accommodate the varying load, i.e., the output of the gasturbine and the boiler may be varied to accommodate variations in load;the output of the gas turbine may be maintained constant and the boilermay accommodate the load variations, i.e., the output of the boiler maybe the only element of the combination that is varied to accommodateload changes; and the output of the boiler may be maintained constantand the gas turbine varied to accommodate load changes, i.e., the outputof the gas turbine may be the only element that is varied to accommodatechanges in the load.

In the first instance, i.e., where the gas turbine and boiler arejointly varied with load change, this operation tends automatically tocompensate for the tendency of the steam temperature to rise with adecrease in load when the weight flow of gas through the boiler remainsconstant. This is so because if the load changes and is accommodatedjointly between boiler and the gas turbine the temperature of the gasturbine gases decreases although the quantity of these gases remains thesame. If the dampers 62 and 69 are not moved from their former positionso that the same quantity of gas turbine gases is supplied to thefurnace the effect of high temperature superheater section 32 is tocause the steam temperature to rise with a decrease in load. However,since the temperature of the gases flowing over low temperaturesuperheater section 44 is decreased and the amount of gases flowing overthis section remains the same the effect on this low temperaturesuperheater section is to decrease the steam temperature. These twoeffects thus work to counteract each other. Since these effects will notbe equal however, the dampers 60 and 62 may be adjusted to provide whatis in the nature of verier control in this instance, with damper 60being moved to decrease the gas flow into the furnace and damper 62moved to increase the proportion of the turbine gases that flows throughbypass duct 22 as the load decreases. Since high temperature superheatersection 32 has a much greater heating effect than low temperaturesuperheater section 44 this adjustment of the dampers will effect adecrease in the steam temperature. Thus as the load on the power plantinstallation decreases a greater proportion of the gases are passedthrough bypass 22 and the steam temperature is maintained constant. Whenthe load is increased the opposite control effect is had.

When the output of the gas turbine is maintained constant and the boileris operated to accommodate the variations in load, dampers 62 and 6% maybe adjusted so as to provide a generally constant steam temperaturethroughout the load range at which the boiler operates. Here as in theinstance where the boiler and gas turbine are varied together, as theload decreases the dampers are manipulated so that an increased portionof the gas turbine gases pass through the bypass 22 and accordingly overthe low temperature superheated section 44. With an increase in load anopposite control effect is bad. With this control the temperature of thesteam delivered to steam turbine 52 may be maintained generallyconstant.

Where the boiler is operated at a constant load and the output of thegas turbine is varied to accommodate the variations in load on the powerplant an opposite control effect from that just described is provided inorder that the temperature of the steam delivered to turbine 52 ismaintained generally constant throughout the load range of operation ofthe gas turbine. As the load on gas turbine 10 decreases, the amount ofgas turbine gases remains constant but the temperature of these gasesdecreases. It is thus necessary to have a larger proportion of thesegases introduced into boiler 29 in order that the steam temperature maybe maintained constant. Therefore as the load on the gas turbinedecreases the proportion of the gases passing through bypass 22 isdecreased with the result that the steam temperature may be maintainedconstant by controllably varying this proportioning. Contrarywise, asthe load on the gas turbine increases a greater proportion of the gasturbine gases is passed through bypass 22 and a lesser proportion isintroduced into the furnace with the control of this proportioningaccordingly being such as to maintain the steam temperature delivered toturbine 52 constant.

It will thus be seen that with applicants novel arrangement an extremelyefiicient operating organization is provided which permits boiler 20 tobe satisfactorily operated when the turbine is not operated, whichprovides an extremely efficient combined operation of the turbine andthe boiler and which provides for steam temperature control when eitherthe gas turbine only swings variations of the common load, the boileronly swings these variations or the gas turbine and boiler togetherswing the variations of load.

While I have illustrated and described a preferred embodiment of myinvention it is to be understood that such is merely illustrative andnot restrictive and that variations and modifications may be madetherein without departing from the spirit and scope of the invention. Itherefore do not wish to limited to the precise details set forth butdesire to avail myself of such changes as fall within the purview of myinvention.

What is claimed is:

1. In combination, a gas turbine engine, a boiler fired with a suitablefuel, the turbine engine being such that the exhaust thereof provides asubstantial excess of oxygen over that required to fire the boiler withthe amount of exhaust gases remaining generally constant over asubstantial load range, means introducing a portion of the turbineexhaust gas into the furnace to support combustion of the fueltherewithin, means bypassing the boiler with the remainder of theturbine exhaust gases, Water heating heat exchange means forming part ofthe economizer surface of the boiler disposed in said bypass means toabsorb heat from the bypassing turbine exhaust gases, additionaleconomizer surface over which both the bypass gases and the gases fromthe furnace pass a superheater for superheating the steam generated bythe boiler and including a low temperature section disposed in saidbypass means and a high temperature section located in the boiler saidlow temperature section and said high temperature section being suchthat the heat absorbed by the high temperature section is substantiallygreater than that absorbed by the low temperature section, and meansprovided to controllably proportion the turbine exhaust gases betweenthe bypass means and the boiler.

2. The combination of a boiler having a furnace fired with a suitablefuel, a gas turbine operative to produce a generally constant amount ofexhaust gases over a substantial load range with the exhaust gasescontaining substantially more oxygen than required to burn the fuel inthe boiler, means for introducing a portion of these gases into theboiler to support the combustion of the fuel therein, means bypassingthe boiler furnace with the remaining portion and passing said remainingportion over steam heating and economizer surface disposed in saidbypassing means and connected into the boiler system, said steam heatingsurface being disposed upstream of said economizer surface in saidbypassing means, additional economizer surface disposed so thecombustion gases generated in the furnace as well as the turbine gasesthat bypass the furnace pass thereover, the boiler having steamgenerating and steam heating surface sufficient to develop the designpressure and temperature at maximum load when the gas turbine is shutdown and the boiler is fired With atmospheric air, the steam heatingsurface, over which the gas turbine gases that bypass the boiler furnacepass, being sufficient to aid the boiler to give this design temperaturewhen operating at maximum load in combination with the gas turbine wheregas turbine exhaust gases are employed as the combustion supportingmedium for the fuel in the boiler and means to controllably proportionthe turbine gases between the boiler furnace and the bypass.

3. In a power plant organization the combination of a vapor generatorhaving a furnace fired with a suitable fuel, a gas turbine engine of thetype wherein the amount of turbine exhaust gases remains generallyconstant over a substantial load range with these exhaust gasesproviding a substantial excess of oxygen over that required to fire saidfurnace, means introducing a portion of the turbine exhaust gases intothe furnace to support combustion of fuel therewithin, means bypassingsaid furnace with the remainder of said gases, said vapor generatorhaving economizer surface a portion of which is in said bypass means toabsorb heat from the bypassing turbine gases, said vapor generator alsohaving vapor heating surface one section of which is disposed in saidbypass before the economizer to absorb heat from the bypassing turbinegases and another section of which is disposed to have the gases fromthe furnace pass thereover, and means operative to controllablyproportion the turbine exhaust gases between the bypass means and thefurnace.

References Cited in the file of this patent UNITED STATES PATENTS1,398,946 Schmidt Nov. 29, 1921 1,925,646 Rakestraw Sept. 5, 19332,107,440 Gordon Feb. 8, 1938 2,223,953 Davis Dec. 3, 1940 2,471,755Karrer May 31, 1949 2,604,755 Nordstrom et a1. July 29, 1952

